1. Field of the Invention
The present invention relates to an oil or fat composition which is effective for reduction of body fat and visceral fat for the prevention of accumulation of such fats, and for prevention and treatment of obesity and related conditions; which exerts an excellent prevention and treatment effect on life-style related diseases caused by accumulated fats, through long-term ingestion of the composition; and which is useful for foods, pharmaceuticals, and pet food or feed.
2. Discussion of the Background
Obesity and life-style related diseases such as hyperlipemia are said to be prevented and treated by changing aspects of the person's lifestyle, such as unbalanced diet and lack of physical exercise. Particularly, they are prevented through reduction of body fat, inter alia, visceral fat, so as to suppress obesity.
Among nutrients, oil and fat, having a high calorific value (9 kcal/g), promote obesity, and induce life-style related diseases. Thus, a wide range of studies have been conducted on anti-obesity oils and fats. For example, U.S. Pat. No. 3,600,186 discloses a technique employing a polyester which is derived from a sucrose fatty acid and is not absorbed by the body. However, the polyester raises problems such as anal leakage and inhibition of absorption of fat-soluble vitamins.
Apart from the polyester, conjugated linoleic acid, fish oil, and perilla oil have been proven to exert effect on reduction of body fat in animal experiments (see Lipids 32, 853 (1997); J. Agric. Food Chem. 46, 1225 (1998); Metabolism 39, 217 (1990); etc.). However, these materials fail to exert ensured effect when administered in small amounts.
Other approaches are based on a glyceride structure that is harmless and causes no adverse side effects during long-term administration. Examples of such approaches include employment of a cholesterol-reducing agent (Japanese Patent Application Laid-Open No. 63-104917); a serum-triglyceride-concentration-reducing agent (Japanese Patent Application Laid-Open Nos. 4-300825 and 5-310567); a body-weight-gain-suppressing agent (Japanese Patent Application Laid-Open No. 4-300826); an agent for preventing and treating fatty liver (Japanese Patent Application Laid-Open No. 4-300828); and a liquid oil composition for general use (U.S. Pat. No. 6,004,611). These approaches are based on an effect attributed to monoglyceride or diglyceride structure and are considered highly safe approaches, in that adverse effects such as anal leakage and inhibition of absorption of fat-soluble vitamins are avoided.
In order to fully attain such effects in treating obesity, a monoglyceride and/or a diglyceride, instead of a triglyceride, must be ingested in large amounts in the form of a product such as cooking oil. However, the cooking oil for attaining these effects is not suitable for a large amount of daily ingestion. In contrast, WO 01/10989 discloses that a diglyceride prepared from an ω3 unsaturated fatty acid having 20 or more carbon atoms exerts the above effects through ingestion thereof in a small amount, and Japanese Patent Application Laid-Open No. 2001-64672 discloses an oil or fat composition containing a monoglyceride and/or diglyceride as an effective ingredient. However, the monoglyceride and/or diglyceride remain unsatisfactory, and demand exists for an oil or fat composition which contains a monoglyceride and/or diglyceride exerting efficacy through ingestion in a smaller amount and which can be easily ingested over a long period of time.